FIG. 4.

Proteolytic activity in media from the late-logarithmic phase of growth of isogenic mutants of the S. aureus strains Newman and SH1000. The activity was visualized either by gelatin-zymography analysis (A) or was quantified using azocasein as the substrate (B). The contribution of V8 proteinase (full arrowhead in panel A and stippled bars in panel B) and aureolysin (empty arrowhead and crossed bars) to total proteolytic activity was determined with the specific inhibitors 3,4-dichloroisocoumarin and o-phenanthroline, respectively.